/**
 * Copyright 2020 Alibaba Group Holding Limited.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.maxgraph.coordinator;

import com.alibaba.maxgraph.common.ServerAssignment;

import java.util.*;

public class DefaultPartitionGroupStrategy implements PartitionGroupStrategy {

    @Override
    public List<List<Integer>> getGroupInfo(Map<Integer, ServerAssignment> assignments) {
        int storeNodeCount = assignments.size();
        Set<Set<Integer>> dedupPartitionsSet = new HashSet<>();
        for (ServerAssignment assignment : assignments.values()) {
            dedupPartitionsSet.add(assignment.getPartitions());
        }
        int nodesPerGroup = dedupPartitionsSet.size();
        if (storeNodeCount % nodesPerGroup != 0) {
            throw new IllegalArgumentException(
                    String.format(
                            "Total node: %s, nodes per group: %s", storeNodeCount, nodesPerGroup));
        }

        List<List<Integer>> groupInfo = new ArrayList<>(); // group -> nodes_list
        int serverID = 1;
        for (int i = 0; i < storeNodeCount / nodesPerGroup; i++) {
            List<Integer> group = new ArrayList<>();
            for (int j = 0; j < nodesPerGroup; j++) {
                group.add(serverID);
                serverID++;
            }
            groupInfo.add(group);
        }
        return groupInfo;
    }
}
